The following configs works on Cent OS 6 or earlier
As stated above first have to disable selinux.
Step 1
nano /etc/sysconfig/selinux
Make sure the file has this configurations
SELINUX=disabled
SELINUXTYPE=targeted
Then restart the system
Step 2
iptables -A INPUT -m state --state NEW -p tcp --dport 8080 -j ACCEPT
Step 3
sudo service iptables save
For Cent OS 7
step 1
firewall-cmd --zone=public --permanent --add-port=8080/tcp
Step 2
firewall-cmd --reload